Conductive member containing coating and preparation method thereof

Abstract

The present application relates to a conductive member comprising a coating layer and a method for manufacturing the same. The coating is arranged on a base body and comprises an amorphous graphite layer arranged on the base body and a strength supporting layer doped with conductive metal. The amorphous graphite layer is arranged between the base body and the strength supporting layer; the strength support layer includes at least one of a metal nitride, a metal carbide, or a metal carbonitride. The coating provided by the invention has relatively good wear resistance, corrosion resistance and conductivity, and is very suitable for use requirements of working conditions such as a fuel cell bipolar plate and the like.

Description

Technical Field

[0001] This application relates to the field of surface treatment technology, and more specifically to a coating and a method for preparing the same. Background Technology

[0002] This application relates to the field of materials engineering technology. Material corrosion has always been a major cause of material loss, therefore, developing a corrosion-resistant coating is essential. However, the application scenarios of products are generally not limited to a single working condition; corrosion resistance, conductivity, and wear resistance are all synergistic requirements. For example, fuel cell bipolar plates have both corrosion and conductivity requirements. This application proposes a coating that can satisfy both corrosion resistance and conductivity and wear resistance requirements. Summary of the Invention

[0003] This application provides a coating for a fuel cell bipolar plate, aiming to address at least one problem existing in the relevant field. This application also provides a method for preparing the coating and a product containing the coating.

[0004] In one aspect of this application, a wear-resistant and corrosion-resistant conductive component is provided, comprising a substrate and a coating disposed on the substrate. The coating comprises an amorphous graphite layer disposed on the substrate and a strength support layer doped with a conductive metal. The amorphous graphite layer is disposed between the substrate and the strength support layer. The strength support layer comprises at least one of the following substances: metal nitride, metal carbide, or metal carbonitride.

[0005] In some embodiments, the conductive metal is selected from at least one of Cu, Ag, Au, and Pt.

[0006] In some embodiments, the atomic percentage of the conductive metal is 7%-30% based on the total number of atoms in the coating.

[0007] In some embodiments, the metal in the metal nitride, the metal carbide, or the metal carbonitride is each independently selected from at least one of Cr, Al, Ti, Ta, Zr, Fe, Cu, Ni, or V.

[0008] In some embodiments, the SP of the amorphous graphite layer 2 The bond percentage is 40%-70%.

[0009] In some embodiments, the coating satisfies at least one of the following (1)-(4):

[0010] (1) The hardness of the strength support layer is 1600HV-2800HV;

[0011] (2) The hardness of the amorphous graphite layer is 600HV to 1200HV;

[0012] (3) The conductivity of the coating is 3-9 mΩcm. 2 ;or

[0013] (4) The corrosion resistance of the coating is 0.1-0.35 μAcm. -2 .

[0014] In another aspect of this application, a method for preparing a conductive component at any location within this application is provided, comprising the following steps:

[0015] (1) An amorphous graphite layer is formed on the surface of the substrate of the component; and

[0016] (2) A strength support layer doped with conductive metal is formed on the amorphous graphite layer.

[0017] In some embodiments, steps (1) and (2) are each independently performed using one of high-power pulsed magnetron sputtering (HIPIMS), medium-frequency magnetron sputtering, or direct current magnetron sputtering (DC).

[0018] In another aspect of this application, this application provides a bipolar plate for a fuel cell, which includes a conductive component or a conductive component prepared by any method described herein.

[0019] In another aspect of this application, this application provides a fuel cell that includes a bipolar plate at any point in this application.

[0020] The coating of this application has good wear resistance, corrosion resistance and conductivity, making it very suitable for use in fuel cell bipolar plates and other similar applications.

[0021] Additional aspects and advantages of the embodiments of this application will be described and shown in part in the following description, or illustrated by practice of the embodiments of this application. Attached Figure Description

[0022] Figure 1 Example 1: Schematic diagram of the coating structure. Detailed Implementation

[0023] The embodiments of this application will be described in detail below. These embodiments should not be construed as limiting the scope of this application.

[0024] In the detailed description and claims, a list of items connected by the terms "at least one of," "at least one of," "at least one of," or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0025] The following descriptions of the embodiments are with reference to the accompanying drawings, illustrating specific embodiments in which the invention can be implemented. Furthermore, the directional terms used in this invention, such as up, down, top, bottom, front, back, left, right, inside, outside, side, surrounding, center, horizontal, transverse, vertical, longitudinal, axial, radial, uppermost, or lowermost, are merely directions with reference to the accompanying drawings. Therefore, the directional terms used are for illustrating and understanding the invention, and not for limiting the invention.

[0026] Regarding the numerical values ​​appearing in this document, given the nature or precision of the measurements, all measured values ​​should be understood to have an acceptable level of error. A typical exemplary level of this error may be within ±10% or ±5% of a given value or range of values.

[0027] conductive components

[0028] In one aspect of this application, a wear-resistant and corrosion-resistant conductive component is provided, comprising a bipolar plate substrate and a coating disposed on the substrate. The coating comprises an amorphous graphite layer disposed on the substrate and a strength support layer doped with a conductive metal. The amorphous graphite layer is disposed between the substrate and the strength support layer. The strength support layer comprises at least one of the following substances: metal nitride, metal carbide, or metal carbonitride.

[0029] In some embodiments, the conductive metal is selected from at least one of Cu, Ag, Au, and Pt.

[0030] In some embodiments, the atomic percentage of the conductive metal is 7%-30% based on the total number of atoms in the coating, for example, it can be 7%, 10%, 15%, 20%, 25% and 30%, or a range of any two of the above values.

[0031] In some embodiments, the metal in the metal nitride, the metal carbide, or the metal carbonitride is each independently selected from at least one of Cr, Al, Ti, Ta, Zr, Fe, Cu, Ni, or V.

[0032] In some embodiments, the SP of the amorphous graphite layer 2 The bond percentage is 40%-70%, for example, it can be 40%, 50%, 60% and 70%, or any combination of the above values. This parameter reflects whether it leans towards the graphite phase or the diamond phase.

[0033] In some embodiments, the coating satisfies at least one of the following (1)-(4):

[0034] (1) The hardness of the strength support layer is 1600HV-2800HV;

[0035] (2) The hardness of the amorphous graphite layer is 600HV to 1200HV;

[0036] (3) The conductivity of the coating is 3-9 mΩcm. 2 ;or

[0037] (4) The corrosion resistance of the coating is 0.1-0.35 μAcm. -2 .

[0038] In some embodiments, the hardness of the coating (i.e., the strength support layer) can be 1600HV, 1800HV, 2000HV, 2400HV, 2600HV, 2700HV, 2800HV, or any combination of the above values.

[0039] In some embodiments, the hardness of the amorphous graphite layer may be 600HV, 800HV, 1000HV or 1200HV, or any combination of the above values.

[0040] In some embodiments, the conductivity of the coating may be 3 mΩcm. 2 4 mΩcm 2 5 mΩcm 2 6 mΩcm 2 7 mΩcm 2 8 mΩcm 2 9 mΩcm 2 or 10 mΩcm 2 , or a range consisting of any two of the above values.

[0041] In some embodiments, the corrosion resistance of the coating is 0.1 μAcm. -2 0.15 uAcm-2 0.2 uAcm -2 0.25 uAcm -2 0.3 uAcm -2 0.35 uAcm -2 , or a range consisting of any two of the above values.

[0042] In another aspect of this application, a method for preparing a conductive component at any location within this application is provided, comprising the following steps:

[0043] (1) An amorphous graphite layer is formed on the surface of the substrate of the component; and

[0044] (2) A strength support layer doped with conductive metal is formed on the amorphous graphite layer.

[0045] In some embodiments, steps (1) and (2) are each independently performed using one of high-power pulsed magnetron sputtering (HIPIMS), medium-frequency magnetron sputtering, or direct current magnetron sputtering (DC).

[0046] fuel cell bipolar plates

[0047] This application provides a bipolar plate for a fuel cell, which includes a conductive component or a conductive component prepared by any method described herein.

[0048] fuel cells

[0049] This application provides a fuel cell that includes a fuel cell bipolar plate at any point in this application.

[0050] The coating of this application has good wear resistance, corrosion resistance and conductivity, making it very suitable for use in fuel cell bipolar plates and other similar applications.

[0051] Additional aspects and advantages of the embodiments of this application will be described and shown in part in the following description, or illustrated by practice of the embodiments of this application.

[0052] Example

[0053] The present application will be further described in detail below with examples and comparative examples, but the present application is not limited to these examples as long as it does not depart from its spirit.

[0054] The coating process described herein uses one of the following: high-power pulsed magnetron sputtering (HIPIMS), medium-frequency magnetron sputtering, or direct current magnetron sputtering (DC). However, those skilled in the art will understand that coating also includes other different forms of thin film deposition technology. Any process that can achieve the technical effects described herein is within the scope of this application.

[0055] Unless otherwise stated, all materials used in this application are commercially available.

[0056] Example 1

[0057] The structural diagram of the coating in this embodiment is shown below. Figure 1 As shown, an amorphous graphite layer 2 and a metal nitride layer 3 doped with conductive metal are sequentially disposed on the substrate 1. The specific fabrication process is as follows:

[0058] 1. Cleaning

[0059] Ultrasonic cleaning

[0060] Product pretreatment before coating: The bipolar plate to be coated is placed in an ultrasonic cleaning line for cleaning. First, it is cleaned with an alkaline bath to remove surface oil stains, then it is neutralized with an acidic bath to remove rust stains from the product surface, and finally rinsed with pure water and baked clean.

[0061] Ion cleaning process

[0062] After the bipolar plates are cleaned, they are pushed into the furnace. The mechanical pump and Roots pump are turned on to roughly evacuate to 5 Pa. Then the holding pump and molecular pump are turned on to evacuate to 5*10-2 Pa. The heating tube is turned on and the heating temperature is set to 150 degrees. Evacuation continues until the pressure is 5*10-3 Pa, and the coating process is ready to begin.

[0063] 2. Amorphous graphite layer

[0064] Ar gas was introduced into the furnace, the graphite target was turned on, and the deposition of an amorphous graphite layer began using high-power pulsed magnetron sputtering (HIPIMS). The gas pressure and bias voltage for film deposition were set to 0.2 Pa and 400 V, respectively, thereby enabling the SP of Example 1 to be deposited. 2 The bonding percentage is 60%. The surface hardness of the amorphous graphite layer in this embodiment reaches 1000 HV.

[0065] 3. Metal nitride layer doped with conductive metal

[0066] Nitrogen and Ar (nitrogen and argon in a 1:1 ratio, total pressure 0.5 Pa) were introduced into the furnace. The Ti metal target and the Ag conductive metal target were activated, and DC pulsed magnetron sputtering was employed. The power of the targets was set to 8 kW for Ti and 2 kW for Ag, resulting in an Ag atomic content of 15%. In this embodiment, the surface hardness of the TiN layer 3 reached 2400 HV.

[0067] 4. Once the coating is complete, the product is cooled and removed from the oven.

[0068] Example 2

[0069] The only difference between Example 2 and Example 1 is that the power of the target material is adjusted, with the Ti target power being 7 kW and the Ag target power being 3 kW, so that the Ag atomic content is 30%.

[0070] Example 3

[0071] The only difference between Example 3 and Example 1 is that by adjusting the gas pressure and bias voltage of the coating to 0.1 Pa and 600 V respectively, the SP of the amorphous graphite layer is made more efficient. 2 The bond percentage is 20%.

[0072] Comparative Example 1: Only amorphous graphite layers were prepared.

[0073] The only difference between Comparative Example 1 and Example 1 is that step 3 is omitted, that is, the metal nitride layer doped with conductive metal is not prepared.

[0074] Comparative Example 2: Only TiN coating was prepared

[0075] The only difference between Comparative Example 2 and Example 1 is that: (1) there is no step 2, that is, no amorphous graphite layer is prepared; and (2) the conductive metal target is not turned on in step 3.

[0076] Comparative Example 3: Preparation of TiN coatings doped with Ag only

[0077] The only difference between Comparative Example 3 and Example 1 is that step 2 was omitted, i.e., no amorphous graphite layer was prepared.

[0078] Performance testing

[0079] SP 2 Content: Raman spectroscopy is a widely used method for characterizing the valence structure of carbon atoms in C thin films. Its principle is based on the Raman scattering effect, which uses the scattered molecular vibrational frequencies and energy levels to characterize the chemical bond types of the tested sample, thereby obtaining information such as bond strength and full width at half maximum (FWHM). In the test, the laser source wavelength was 532 nm, the wavenumber range was 800–2000 cm⁻¹, and the operating power was 10 mW.

[0080] Ag content: X-ray energy dispersive spectroscopy (EDS) is a very intuitive analytical method. Its principle lies in the interaction between electrons and natural substances, allowing the collection of microscopic electronic information from the sample. This information can then be used to characterize the sample. The former reveals the microscopic morphology, while the latter characterizes the composition of the substance. An electron beam is focused and scanned on the sample surface, exciting various secondary and backscattered electrons, thus obtaining information about the sample and representing its composition. The test uses a field emission scanning electron microscope (FE-SEM, FEINova400, USA) and its accompanying energy dispersive spectroscopy (EDS) with an accelerating voltage of 10 kV.

[0081] Hardness: Nano-indentation test, ISO14577-1-2015 Metallic materials. Indentation hardness and material parameters of indentation;

[0082] Conductivity: Wang's improved method for testing the resistance of carbon paper-coating samples, specifically the contact resistance. The sample is placed between two sheets of Toray conductive carbon paper, supported on the outermost side by a copper plate. During the test, a pressure device is used to uniformly pressurize the copper plate, followed by uniformly pressing the coated sample. A constant current (500mA) is provided through the copper plate, and Ohm's law is used to calculate the contact resistance of the coated sample by measuring the voltage.

[0083] Corrosion resistance: Electrochemical testing was conducted using a three-electrode system with sulfuric acid at pH 3 as the corrosive medium. The sample under test was used as the working electrode, a saturated calomel electrode (SCE) as the reference electrode, and a platinum plate as the auxiliary electrode. The sample was immersed in the solution for 30 minutes to obtain electrochemical stability. Then, the potentiodynamic polarization curve was scanned from -0.6 to 0.7 V (relative to SCE) at 0.001 V / s. In the potentiostatic polarization test, the externally applied potential in the cathode and anode environments was +0.6 V (SSCE) in the cathode and -0.1 V (vs SCE) in the anode for 2 hours.

[0084] Table 1. Test results for each embodiment and comparative example

[0085]

[0086] As shown in Examples 1 and 2, the higher the Ag content, the higher the hardness. However, if the Ag content reaches 30%, the conductivity will decrease due to agglomeration.

[0087] As shown in Examples 1-3, SP 2 Higher carbon content results in better electrical conductivity, but lower hardness. When SP in Example 3... 2 When the carbon content drops to 20%, the hardness increases but the conductivity decreases significantly.

[0088] As shown in Comparative Examples 2-3, the corrosion resistance is significantly reduced because no amorphous graphite layer was prepared.

[0089] As shown in Comparative Example 1, the hardness of the metal nitride layer doped with conductive metal was significantly reduced because no conductive metal doping layer was prepared.

[0090] It should be noted that the coating provided in this application can be applied not only to bipolar plates of fuel cells, but also to other fields that require corrosion resistance, conductivity, and wear resistance.

[0091] Throughout this specification, references to "some embodiments," "partial embodiments," "one embodiment," "another example," "example," "specific example," or "partial example" mean that at least one embodiment or example in this application includes a specific feature, structure, material, or characteristic described in that embodiment or example. Therefore, descriptions appearing throughout this specification, such as "in some embodiments," "in an embodiment," "in one embodiment," "in another example," "in an example," "in a specific example," or "example," do not necessarily refer to the same embodiments or examples in this application. Furthermore, specific features, structures, materials, or characteristics described herein can be combined in any suitable manner in one or more embodiments or examples.

[0092] Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments should not be construed as limiting the present application, and that changes, substitutions and modifications can be made to the embodiments without departing from the spirit, principles and scope of the present application.

Claims

1. A wear and corrosion resistant electrically conductive member comprising a substrate and a coating layer provided on the substrate, the coating layer comprising an amorphous graphite layer provided on the substrate and a strength support layer doped with an electrically conductive metal; the amorphous graphite layer is provided between the substrate and the strength support layer; the strength support layer comprises at least one of a metal nitride, a metal carbide or a metal carbonitride.

2. The electrically conductive member according to claim 1, wherein the electrically conductive metal is selected from at least one of Cu, Ag, Au and Pt.

3. The electrically conductive member according to claim 1, wherein the atomic percentage of the electrically conductive metal is 7-30% based on the total atomic number of the coating layer.

4. The electrically conductive member according to claim 1, wherein the metal of the metal nitride, the metal carbide or the metal carbonitride is each independently selected from at least one of Cr, Al, Ti, Ta, Zr, Fe, Cu, Ni or V.

5. The conductive member according to claim 1, wherein the amorphous graphite layer has a SP 2 bonding percentage of 40-70%.

6. The electrically conductive member according to claim 1, wherein the coating layer satisfies at least one of the following (1)-(4): (1) the strength support layer has a hardness of 1600 HV-2800 HV; (2) the amorphous graphite layer has a hardness of 600 HV to 1200 HV; (3) the coating has an electrical conductivity of 3-9 mΩcm 2 ; (4) the corrosion resistance of the coating is 0.1-0.35 uAcm -2 .

7. A method for producing the electroconductive member according to any one of claims 1 to 6, characterized by, comprising the steps of: (1) forming an amorphous graphite layer on a surface of a substrate of a member; and (2) forming a strength support layer doped with an electrically conductive metal on the amorphous graphite layer.

8. The method according to claim 7, wherein each of the steps (1) and (2) independently employs one of high power impulse magnetron sputtering (HIPIMS), medium frequency magnetron sputtering, direct current magnetron sputtering (DC).

9. A bipolar plate for a fuel cell, characterized by an electrically conductive member according to any one of claims 1-6 or a method according to claim 7 or 8.

10. A fuel cell characterized by comprising: a bipolar plate comprising the electrically conductive member according to claim 9.

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